Position indicator for a display system

ABSTRACT

The invention relates to a position indicator which rides over a surface for controlling a cursor over a visual display. The indicator generates signals indicative of its positions to cause the cursor to be displayed on the display at a corresponding position. The indicator includes a control mechanism that comprises a transport sphere in combination with position wheels indicative of Cartesian coordinates. The sphere is in contact with the surface over which the indicator rides and the position wheels contact the sphere at a position on the sphere approximately 90* from the contact loci of the sphere and the surface.



1. Position indicator apparatus for a display system controlled by a computer whereby the display is alterable in accordance with signals delivered to said computer which indicate positions on said display and changes desired to be made therein, said apparatus being movable over a surface to provide position indications corresponding to positions on said display, comprising: a housing, means for supporting said housing on said surface and transporting said housing over said surface, said means comprising spherical means in contact with said surface, said spherical means further comprising means for translating the movement of said housing into radial information, and transducer means responsive to said spherical means for delivering signals to said computer for indicating the movement and position of said housing.
 2. The position indicator apparatus of claim 1 wherein said transducer means includes referencing means for translating said radial information into Cartesian information which is represented by respective signals delivered to said computer.
 3. The position indicator apparatus of claim 2 wherein said referencing means comprises at least two rotational means in contact with said spherical means which are coupled to respective potentiometer means for delivering said respective signals.
 4. The position indicator apparatus of claim 3 wherein said spherical means is a sphere and said rotational means are wheels in contact with said sphere responsive only to the movement of said sphere, said sphere being in contact with a surface over which said indicator means is moved and thereby responsive to the movement of said indicator meaNs.
 5. The position indicator apparatus of claim 4 wherein two of said wheels contact said sphere at a position on said sphere approximately 90* from the contact loci of said sphere and the surface.
 6. Position indicator apparatus for a display system controlled by a computer whereby the display is alterable in accordance with signals delivered to said computer which indicate positions on said display and changes desired to be made therein, said apparatus being movable over a surface to provide position indications corresponding to positions on said display, comprising: a housing, means for supporting said housing on said surface and transporting said housing over said surface, said supporting means including spherical means constrained within said housing in contact with said surface for translating the movement of said housing into radial information, and transducer means responsive to said spherical means for delivering signals to said computer for indicating the movement and position of said housing.
 7. The position indicator apparatus of claim 6 wherein said transducer means includes referencing means for translating said radial information into Cartesian information which is represented by respective signals delivered to said computer.
 8. The position indicator apparatus of claim 7 wherein said referencing means comprises at least two rotational means in contact with said spherical means which are coupled to respective potentiometer means for delivering said respective signals.
 9. The position indicator apparatus of claim 8 wherein said spherical means is a sphere and said rotational means are wheels in contact with said sphere responsive only to the movement of said sphere, said sphere being in contact with a surface over which said indicator means is moved and thereby responsive to the movement of said indicator means.
 10. The position indicator apparatus of claim 9 wherein two of said wheels contact said sphere at a position on said sphere approximately 90* from the contact loci of said sphere and the surface.
 11. The position indicator apparatus of claim 10 wherein the axes of said wheels are substantially perpendicular to each other.
 12. The position indicator apparatus of claim 1 wherein said spherical supporting means is constrained in the vertical coordinate within said housing in a direction away from said surface at a point of tangency with its outer surface.
 13. The position indicator apparatus of claim 12 wherein said supporting means further comprises at least two supporting elements attached to said housing, which elements in combination with said spherical supporting means comprises at least a tripodal supporting means for said indicator.
 14. The position indicator apparatus of claim 13 wherein said spherical supporting means is unconstrained in the opposite direction of said vertical coordinate within said housing such that said spherical means remains in contact with said surface even if said surface has irregularities. 